Add option to use Shift key to move cursor when typing in buffer

[ottokang]

Is your feature request related to a problem? Please describe.
Like PIME function ( commit log ), user can use LShift or RShift to move cursor when typing in buffer.

Describe the solution you'd like
Add an option to enable this Shift key behavior.

Additional context
This option will conflict #619 , so it should have some notification like PIME